n = int(input());x=[0]*n
a = [input().split() for _ in '1'*n]
for i in range(n):
    for j in range(n):
        if a[i][j] == 'nyanpass': x[j]+=1
mx=max(x)
if mx and len([i for i in x if i==mx])==1:
    print(x.index(mx)+1)
else:
    print(-1)